This invention relates to a method and apparatus for building and shaping a tire with preshaped components positioned in the tire at the same spacing as in the cured tire so that the other components will substantially conform to the shape of the preshaped components in the shaped tire. Also by substantially preshaping the tire to the cured shape the edges of the plies are turned up around the bead and set in predetermined turned up positions that will not be appreciably changed in the tire press.
In U.S. Pat. No. 5,262,115 a method of producing a tire bead filler assembly is described wherein the bead filler is preshaped and cured about the bead before building in the tire. The advantage of this method is that the bead filler assembly keeps its shape during building of the tire and also the time required for curing the tire in a tire press may be reduced. One of the problems of using precured tire componets is that the other tire components are not shaped to the cured tire shape until the tire is finally shaped in a tire press. This results in repositioning of the tire components in the tire press which is difficult to control with precision and may affect tire quality.
Tire shaping drums, such as the drum shown in U.S. Pat. No. 5,405,484 have been utilized for shaping tire components, however, no provision has been made for shaping the uncured components to the cured tire shape. One of the reasons for not fully shaping the tire has been the limited force available for pushing the beads toward the cured tire positions. Also, no provision has been made for retaining the beads in the pocket assemblies of the drum if the tire were to be shaped to the cured shape. Also the bladder hinge points are not secured to prevent pulling the plies under the tire bead.
In accordance with the present invention, a new and improved shaping drum and method of building a tire with preshaped components is provided. The shaping drum has segmented pocket assemblies for gripping preshaped bead apexes and moving them to the spacing of the cured tire during shaping of the tire into a belt-tread assembly. The tread may also be precured so that when the tire is cured, the only time required for vulcanization in the tire press is the curing time required for the remaining uncured components.
In accordance with the present invention, there is provided a method of building a tire with a shaping drum having an expandable inboard pocket assembly, an expandable outboard pocket assembly, an inflatable inboard turnup bladder, an inflatable outboard turnup bladder, an inboard sealing flap and an outboard sealing flap connected to said outboard pocket assembly and said inboard pocket assembly comprising:
a. transferring a tire band to a position over the drum,
b. positioning an outboard tire bead over the outboard pocket assembly and an inboard tire bead over the inboard pocket assembly,
c. expanding the outboard pocket assembly and the inboard pocket assembly into sealing engagement with the inboard tire bead and the outboard tire bead,
d. transferring a tread belt assembly to a position over the tire band,
e. inflating the inboard turnup bladder, the outboard turnup bladder and the tire band to expand the tire band into the tread belt assembly, characterized by:
f. simultaneously moving the inboard pocket assembly and the outboard pocket assembly toward a center line of a drum to positions spaced apart a distance which is substantially the same as the distance between the beads of the tire in the cured condition,
g. applying a preshaped component of the tire to the tire band in the cured shape of the tire,
h. stitching the tire tread belt assembly to the expanded tire band with a roller,
i. deflating the inboard turnup bladder, the outboard turnup bladder and the tire band,
j. retracting the inboard pocket assembly and the outboard pocket assembly; and
k. removing the tire from the drum
In accordance with another aspect of the invention, there is provided a tire shaping drum comprising a shaft rotatably mounted on a support member at an inboard end of the shaft, an outboard drum section and an inboard section slidably mounted on the shaft at spaced apart positions, screw means mounted in the shaft and operatively connected to the inboard drum section and the outboard section for moving the inboard drum section and the outboard drum section together and apart upon rotation of the screw, each inboard drum section and outboard drum section having a cylindrical frame, a plurality of bead pocket segments mounted on each frame and spaced circumferentially around the shaft, radially extending spoke members attached to each of the bead pocket segments and slidably mounted in radially extending slots in the frame, piston cylinder assemblies mounted on the drum sections having pistons connected to sliding cams engagable with the spoke members to radially expand the pocket segments for retaining a shaping bladder and providing a bead seat characterized by each of the segments having a circumferentially extending channel for mounting a first edge and a second edge of the bladder, a flange on a first side of the channel and a removable nose piece on a second side of the channel for removal during mounting of the first edge and the second edge of the bladder in the channel with a minimum stretching of the first edge and the second edge of the bladder.
In accordance with a still further aspect of the current invention, there is provided a pocket assembly for a tire building drum of the type having a plurality of circumferentially spaced expandable segments for retaining a shaping bladder and providing a bead seat characterized by each of the segments having a circumferentially extending channel for mounting a first edge and a second edge of the bladder, a flange on a first side of the channel, and a removable nose piece on a second side of the channel for removal during mounting of the first edge and the second edge of the bladder in the channel with a minimum stretching of the first edge and the second edge of the bladder.